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Timing a 6.5

Discussion in 'GM 6.5 Diesel Engines' started by matuva, Jul 19, 2009.

  1. It might appear to most of us that this si going to be a dumbass question.

    Though, I spent an hour debating with my father in law how to time a 6.5

    I told him :

    1. time first the engine. To do so, align the mark on the crankshaft gear with the one on the camshaft gear Engine timing.jpg
    2. Then, rotate the crankshaft 360° counter clokwise. doing so, the mark on the cranshaft will be again at the same place, but the camshaft will have rotate 180° only, and the mark will sit on the opposite
    3. so, you're now ready to align with the IP gear so as to time the IP IP timing.jpg
    4. Timing is done.

    Am I correct or not ?
  2. DMDK

    DMDK Diesel Obsessive

    Sep 3, 2008
    matuva- awesome pics in the garage!!! and the truck looks good too (lol).
    no seriously I would love to live there

    on the post you said ''counter clockwise'' but arrows indicate clockwise direction (that isn't like when you flush the toilet it rotates the opposite direction - lol just kidding !!
  3. Missy Good Wench

    Missy Good Wench Wild Blonde from Cloud Mt

    Nov 19, 2008
    Newberg Oregon
    Right from the "MA GENERAL BOOK" Align the cam spocket and crank sprocket marks.
    Install the cam gear. (keyed, can't screw it up)

    Rotate the crank to place #1 piston at TDC (Firing position with both valves closed)
    Cam gear marks will be at 12 Oclock. Install pump gear so mark aligns with cam gear mark.

    Install IP. The IP will only install one way.

    The three bolts have an asymetrical pattern (not the same) plus the dowel pin goes into the slot in the gear.

    Done deal.

    I was wondering if it was possible to screw this up, so I went down to the shop and ripped the water pumpand cover off my fresh engine for the DaHoooley and looked things over and rotated the thing through several times and watched the timing marks and such.

    The number one piston comes up to fire every two rotations of the crank.

    Fire, power stroke, (1/2 revolution) exhaust stroke (1/2 revolution) Now we have made one complete turn of the crank. Intake stroke (1/2 Revolution) compression stroke (1/2 revolution) at TDC we have made two complete revolutions of the crank and the cam has turned once.

    No matter how you do this, you can't screw it up. As long as the chain sprockets have the marks aligned and then the cam gear is placed at the top and the pump gear has its mark aligned, its right.

    Now there is a tool that is used to mark the timing cover housing where the IP goes in.

    With the #1 piston at TDC the tool is fastened to the pump gear and to the housing (without the gasket) There is a handle on the tool that is turned to take the slack from the chain and there is a marking device on top of the tool the when struck with a hammer will mark the housing at true TDC.

    This tool is of minimal use with the DS4 injected engines.

    When I am pulling an engine down to rebuild it and the IP is good, I mark the IP and the housing so that the IP can go back where it was.

    A nice clean sharp little chisel mark across the two will suffice.

    The electronics will still be set to the original timing point that was being used when the engine last ran.

    This is stored in the ECM's memory and unless a TDC learn and timing procedure is done it wont change.

    Now if you start mixing and matching pumps and rigs and ?????????????/ things can get a tad dicey.

    As long as its close the thing will run and you can then do the timing procedure and bring it in where it needs to be. spec I believe is -1.94 degrees Nominal.

    I believe the actual timing at the crank is about 3.5 degrees BTDC

    Hope this helps

    Missy Good Wench
  4. Yup, nice country, a bit pricey, but nice ;)

    You're right clockwise, not counter clockwise.
    Was past midnight when I was posting ):h
  5. thanks for the write up Missy :thumbsup:

    So, if I understand fine, when you have cam and crank sproket marks facing aligned, the engine is timed, piston #1 being on top at finishing exhaust stroke.
    At this point, crank mark is a 12 o'clock, cam sproket mark is at 6 o'clock

    Rotating crank 1 revolution will place piston #1 on top, at TDC, finishing compression stroke and ready to fire for power stroke the next crank 1/2 revolution.
    Cam sproket will have made 1/2 revolution, and the timing mark on it will be facing the opposite, where you can then align with the mark on the IP gear.
    crank will be a t 12 o'clock, and cam at 12 o'clock, IP at 6 o'clock

    That's it ?
  6. Missy Good Wench

    Missy Good Wench Wild Blonde from Cloud Mt

    Nov 19, 2008
    Newberg Oregon
    With crank and cam marks aligned then turn crank to set #1 on TDC of compression stroke.

    This will place the cam gear with the mark facing straight up. Index the pump gear so its marks match and install the pump.

    Basically no matter how you do it as long as the cam gear mark is at 12 Oclock and the IP gear marks match it will work.

    You cant screw it up as long as the cam and crank were set right and the cam and the pump marks matched.

    YESSSSSSSSS thats it :D:smile5::D

    I took the front back off mine and screwed around to see if it was possible to muck it up. Nope can't be done as long as the marks are matched up.

    Have fun
  7. Thanks Missy ;)

    Oh, BTW, I've been reading with great attention about your rebuild : my hat down !

    ... and I like the CAT yellow :thumbsup:
  8. pronghorntractorworks

    pronghorntractorworks Member

    Jun 22, 2012
    maybe a stupid question, but do the cam and ip marks align when the gear is meshed and fully installed, or before it is installed. if you line the marks up and mesh the gears, the ip gear is off just a bit....
  9. bison

    bison Well-Known Member

    These gears are helical so the dots line up only with the teeth fully meshed, so yes after install.

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